The field of this invention has to do with pipe welders and more particularly to a pipe welder which is specifically adapted to make high quality welds within thin walled piping.
One common use of thin wall piping has to do with muffler systems for internal combustion engines. Such muffler systems are in widespread use in conjunction with motor vehicles. A muffler system includes the muffler with piping extending to the input side of the muffler and with piping extending from the output side of the muffler. This piping is constructed of thin walled material which is usually steel. Also, this piping is normally not straight, that is, not extending in a straight line from the input side of the muffler and from the output side of the muffler. This piping normally is bent in numerous specific bends so that when placed in conjunction with the undercarriage of the motor vehicle, that this piping will be located in specific areas and not interfere with operating parts of the motor vehicle. It is normal that this piping is threaded through empty spaces located within the undercarriage of the motor vehicle.
This threading of this piping through the undercarriage generally results in the forming of a plurality of piping joints. Each piping joint must be totally sealed. Sealing by using of adhesive or rubber seals have a tendency to deteriorate in time. It is important in the constructing of a muffler system that all seals be one hundred percent effective (no leakage) and will not deteriorate as the years go by. A leaky muffler system can be a health hazard to the occupants of the motor vehicle. Also, in this day and age, it is against environmental regulations to have motor vehicle engine exhaust discharged directly into the atmosphere without passing through the muffler system which generally includes a catalytic converter. The reason for this is to diminish the pollution of the air.
In order to produce the most effective seal, the common technique is to weld each joint within the muffler system. However, this welding has to be carefully accomplished because of the thin walled construction of the muffler piping. In the past, it has been common to accomplish this welding manually. However, manually frequently causes the production of inferior welds with these welds producing leakage. Also, it is very easy to create a "hotspot" in the welding procedure which will result in creating of a hole through the muffler piping which results in an unusable product. It has been common that the rejection rate in conjunction with the construction of muffler piping by using of a manual welding technique is approximately twenty percent. This constructing of the muffler piping is in conjunction with the motor vehicle assembly line.
It has been known to use automatic welding equipment to weld pipes. This type of equipment is commonly used in conjunction with pipes of all kinds with generally the side walls of these pipes being greater in thickness than the piping side wall in conjunction with the muffler system. Because of the thin walled nature of muffler piping, the automatic welding is far more difficult than with most piping.
The common procedure in conjunction with an automatic welding device is that a welding electrode is moved three hundred sixty degrees around the weld joint creating a desirable weld. It has been found that in moving of the welding electrode in the downward direction, that is along with the direction of the pull of gravity, that a satisfactory weld is produced. However, when the welding electrode begins to move in a direction against the pull of gravity, the weld bead tends to "puddle" creating "hotspots" resulting in the creating of holes within the piping. Therefore, it has been found that the typical automatic welding procedure has not been satisfactory when used in conjunction with muffler piping.